As described in Patent Literature 1, the flame retardant corrugate tube made of a flame retardant composition which is produced by combining a specific bromine-based flame retardant with a polyolefin has conventionally been known as a protective member of electric wires in an automobile. Although this flame retardant corrugate tube has fire retardancy, in general, its tolerable maximum temperature for continuous use is around 80 to 90 degrees C. because a polyolefin is used. Higher heat resistance is required for the wire protective member.
In recent years, demand for EV (Electric Vehicle) and HEV (Hybrid Electric Vehicle) and like has been increasing. For these kinds of vehicles, high voltage wires can be routed under the floor. The high voltage wire transmits large current and generates high heat, so it requires heat resistance. In case the heat resistance is required, a corrugate tube using a polyamide 6 (PA6) instead of a polyolefin is usually used. (see Patent Literature 2)